Over time he learned that to he could find some of his answers through science. As he realized that many of his questions about the universe went beyond biology or chemistry, Riess found his way to physics—and then to astrophysics.

Today Riess is still asking questions, only they’re different questions.

“When I was a kid, I didn’t think about anything beyond the stars,” Riess said. “The stars that we see are very local just within the Milky Way Galaxy. Then there are vast spaces between the galaxies, and then there are other galaxies.”

Riess is the Thomas J. Barber Professor in Space Studies at the Krieger School of Arts and Sciences at Johns Hopkins University, an astronomer at the Space Telescope Science Institute, a member of the National Academy of Sciences—and in 2011 was named a co-winner of the Nobel Prize in Physics.

“It almost seems to defy that you could ask or answer such a question,” he said. “It isn’t unknowable, but like the famous Einstein quote, ‘The most incomprehensible thing about the universe is that it’s comprehensible.’”

The Expanding Universe

Thanks to a discovery Edwin Hubble made in the 1920s, physicists have known for generations that the universe is expanding. So, if the universe was once smaller and is growing larger, the question always was what will happen next?

“That’s a question cosmologists have been asking for decades,” Riess said. “When you toss a pair of keys in the air, your expectation is that, even though the keys are moving up, at some point they are going to stop and come back down because of gravity. Well, likewise, there is a tract of gravity between all the objects in the universe. So you might think the universe would stop expanding at some point because of the tract of gravity.”

That would depend on how fast the universe is expanding, though, and how quickly everything is moving, and how much everything weighs. By looking at exploding stars called supernovae and considering how long the light takes to reach Earth, physicists could basically look back in time.

Understanding Dark Energy

It was this discovery of the accelerating expansion of the universe by observing supernovae that earned Riess and two other physicists the Nobel Prize.

“We assumed the expansion would be slowing down. Instead, we realized it was speeding up. It would be like tossing your keys in the air and wondering if they are slowing down enough to fall back to Earth… and actually finding out they are going up—faster and faster, as if there was a rocket on the keys. It’s the opposite of what gravity would do,” Riess explained.

“What we discovered is that the ‘rocket’ is this new component of space called dark energy, which is kind of springy and pushing the universe apart, faster and faster.”

Although physicists don’t fully understand the properties of dark energy, teams of scientists around the world are studying it.

“What we’re finding is that ‘nothing’—the vacuum of empty space—is actually much more complicated than we thought. There are particles and activity and funny gravity and all kinds of stuff making up this ’empty’ space. And there’s some kind of material there that acts to give particles their mass,” Riess said. “We are discovering more about the nothingness of space.”

Dark energy raises new questions.

“It’s amazing that we go out with our telescopes and look at really cool objects. And that part is fun. But at the end of the day, we have these questions that are very metaphysical—but they are very scientific. There’s no philosophizing. We’re making a lot of measurements, doing a lot of data crunching.”

Even as the scientists gather data, and look forward to the launch of space telescopes in the 2020s to focus on studying dark energy, they realize they need someone to help make sense of their results.

“We’re waiting for the next Einstein to come along to synthesize everything, because theory and observation works hand in hand, but there’s no substitute for that really brilliant person who can come up with the ideas explain it,” Riess said. “We can’t predict when that will happen.”

Winning the Nobel Prize

Riess also couldn’t have predicted that he would win the Nobel Prize.

The Nobel Committee doesn’t even release the names of people who are being considered for the award.

“You get some inkling that it’s possible,” said Riess. “The typical time between doing the research and the awarding of the prize is 30 years. For a few years, you start being contacted by NPR the day before, asking where will you be when the announcement is made. That went on for a couple years. And then, just about the year it happened, I thought, ‘Oh, this could go on forever. I’ve got to put this out of my mind and not think about it.’ And I got a telephone call.”

It was 5:30 a.m. His 1-year-old son was fussing in his crib, and Riess was trying to decide whether to get up or go back to sleep when the phone rang.

“I picked up the phone, and there were Swedish-sounding people who said, ‘Is Dr. Riess there? We have something important to tell him. You’ve just been awarded the Nobel Prize.’ Then all hell breaks loose, and the phone is ringing, ringing, ringing.”

Riess remembers walking his daughter, who was 7, to school that day.

“All these people were saying, ‘Congratulations!’ and she said, ‘How do they all know? Why are they so excited?’” Riess said. “I said to her, ‘This is pretty unusual. You know how you get a big gold star on your test? This is like a big gold star that everyone knows about.’”

Riess and his wife took their children with them to Stockholm, where he accepted the Nobel Prize. And he went to the White House where President Barack Obama jokingly said to him, “It’s so good to meet people who really earned their Nobel Prize.”

A New Perspective

Today Riess enjoys the freedom that comes with being a Nobel Prize winner who continues to conduct research, all with a different perspective.

“I’ve been working on a project for three years, and I think it’s going to work out. But I’ve never worked on something so long where every day I don’t know if it’s going to work. I would have been in a panic if it were a decade or two ago,” he said.

“That’s the ultimate freedom. You’re not trying to impress anybody. You’re doing something for the love of science, for the love of the questions, for the love of the pursuit of the answers—and without people judging if you’re making progress.”

When Riess speaks to young people, he encourages them to identify something they find compelling.

“When you’re a kid, lots of kids are interested in space and dinosaurs. At some point, do we stop becoming interested in space and dinosaurs? Or do people say, ‘You know, you can’t really make a living as a paleontologist, and there aren’t many paleontology jobs available.’ “You have to make some compromises. But if you can discover that thing you love and work your tail off, that’s really what it’s all about,” Riess said.

“I feel I don’t work a day in my life, because I get the opportunity to do what I’m doing.”